Western branch of the Main Trunk Sewer in Doha South Sewage Infrastructure Project completed

07 Jan 2018 - 18:34

AFP

Doha: Ashghal celebrated the completion of tunneling works in the Western branch of the Main Trunk Sewer of the Doha South Sewage infrastructure project today.

The Tunnel Boring Machine (TBM) broke through into the wall of the tunnel shaft, in the presence of Abdulla Hamad Al Attiyah, Assistant President of Ashghal, and Khalid Saif Al-Khayareen, Drainage Networks Projects Department Manager, along with a number of officials and engineers from the project’s consulting and contracting companies.

This major milestone represents the completion of one of the three main branches forming the Main Trunk Sewer of Doha South Sewage infrastructure project, which will direct the sewage flows through pumping stations to the existing Doha South Treatment Works.

The tunnel extends five kilometres underground reaching several areas including Al Sadd, Al Maamoura, and Salwa Road, up to the Doha South Sewage Treatment Works. Al Attiyah noted that today’s achievement shows that Ashghal is making progress in all its roads, expressways, buildings projects as well as the infrastructure and drainage projects that are being carried out deep underground.

He added that these achievements prove that Qatar is able to move ahead and deliver projects with the required quality and as scheduled.

The Western branch is one of the three parts of the Main Trunk Sewer which will serve Al Sadd, Al Maamoura, Umm Ghuwailina, and Al Matar areas.

Al Khayareen pointed out that the main tunnel will withdraw the drainage water in a smoother way via gravitational factors to get it to the treatment plants, which will contribute to remove around 20 old pumping stations.

The Western branch of the Main Trunk Sewer, which was completed today, stretches from Al Thumama Area to Salwa Road through Abu Hamour Area, with a length of about 5-kilometres, representing about 30% of the total length of the main tunnel.

The tunneling works, which started in the beginning of January 2017, took a period of 12 months at an average rate of 13.7 metres per day.

Tunneling works were implemented using a TBM named “Al Zubara”, one of the two TBMs used in the project, which were designed specifically for the geological features encountered in Doha.

Excavation works were implemented using the Earth Pressure Balance (EPB) tunneling technique, which is ideal for Doha's soft ground and rock conditions, at a depth ranging between 30 to 40 metres, without impacting the traffic flow or the buildings surrounding the tunnel.

Three branches
The Main Trunk Sewer of Doha South Sewage infrastructure project comprises three branches; Eastern, Western, and Northern with a total length of 16 kilometres.

The Eastern branch extends for about 7.5 kilometres from Al Thumama to Old Airport area, passing through the E-Ring Road, and tunnelling works are expected to be completed in Q3, 2018.

The Northern branch extends for about 4 kilometres from Al Thumama to Rawdat Al Khail area, through Al Najma area, and is expected to be completed in Q4, 2018.

The Main Trunk Sewer is being constructed using pre-cast segments, where it takes six segments to build one concrete ring of the tunnel, which includes 13,537 concrete rings with an internal diameter of three metres.

The project also includes the construction of seven lateral interceptor sewers with a total length of about 24 kilometres, which will convey flows from areas in the centre of Doha to the main tunnel.

This is in addition to the construction of 11 shafts at a depth ranging from 20 to 40 metres, which will be used to excavate the main tunnel. To minimise the impact and space of construction works within the city of Doha, four of these shafts will be excavated using a Vertical Shaft Machine. The shafts also lead to inspection rooms that will be constructed as part of the project, through which inspection and periodic maintenance to ensure proper operations of the tunnel's facilities.

The Doha South Sewage Infrastructure Project is designed to serve areas in the south of Doha and the expected growth in population. The project can be linked to future infrastructure projects, and when completed, it will enable the decommissioning of more than twenty old pumping stations currently located in the residential and commercial areas in the south of Doha.

One of the important benefits of the project is the gravity based main trunk sewer that will link a number of areas in the south of Doha to the sewage network. As a result, it will reduce the environmental impacts through the full control of odours in sewage treatment works and conveying system, and reduce other environmental problems arising from sewage overflow due to excess hydraulic pressure on the existing drainage network, where sewage flows exceed its capacity.

Ashghal started implementing the Doha South Sewage Infrastructure Project in August 2015, and 70% of the works are completed so far. The project is planned to be completed in Q1, 2019.

Doha South Sewage Infrastructure Project is the first project in the region to implement the ‘CEEQUAL’, an international evidence-based sustainability assessment, rating and awards scheme for civil engineering, infrastructure, landscaping and works in public spaces.

The Joint Venture “Bouygues Travaux Publics” and “UCC” is the project contractor and “CH2M” is the Project Management Consultant.